高温热解对污泥炭特性及其重金属形态变化的影响
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摘要
温度是影响污泥热解产物性质的主要因素之一。研究了热解温度(550,700,850℃)对污泥炭性质、结构和重金属含量及其形态变化的影响。结果表明:污泥炭产率(55. 83%)和H/C(0. 05)在热解温度为850℃时达到最小值。而当热解温度为700℃时,其pH值、比表面积及污泥炭中各重金属总量与残渣态百分比(F4)均为最大值,同时其所含各重金属中生物有效态(F1+F2)的质量分数也均为最低值,即污泥中各重金属潜在的生态风险水平处于最低水平。而当温度升至850℃时,污泥中各重金属相对稳定态质量分数(F3+F4)有所减小,这可能是由于高温条件下金属易随热解气挥发所导致。故700℃是提升污泥炭质量和钝化污泥中重金属、降低其生态风险的最佳温度。
Temperature is one of the key factors which govern the characteristics of the pyrolysis product of sewage sludge. This paper investigated the effect of different pyrolysis temperatures( 550,700 and 850 ℃) on the property,ultrastructure of sludge biochar as well as heavy metal contents and speciation changes inside. The results showed that sludge carbon yield( 55. 83%) and H/C( 0. 05) reached the minimum value at 850 ℃. When the pyrolysis temperature was 700 ℃,the pH value,specific surface area,the total amount of heavy metals in sludge carbon and the percentage of residual state( F4) were all the maximum. At the same time,the bioavailable concentration( F1+F2) of heavy metals dropped to the minimum. In other words,the ecological risk of the heavy metals contained in the sludge was minimized. However,when the temperature was raised to 850 ℃,the percentage of stable heavy metal speciation( F3+F4) declined to some extent,which might be caused by volatilization of metals with pyrolysis gas at high temperature. The outcomes of this study implies that 700 ℃ was the optimal temperature for improving sludge biochar,immobilizing the heavy metals in sludge and minimizing their ecological risk.
Temperature is one of the key factors which govern the characteristics of the pyrolysis product of sewage sludge. This paper investigated the effect of different pyrolysis temperatures( 550,700 and 850 ℃) on the property,ultrastructure of sludge biochar as well as heavy metal contents and speciation changes inside. The results showed that sludge carbon yield( 55. 83%) and H/C( 0. 05) reached the minimum value at 850 ℃. When the pyrolysis temperature was 700 ℃,the pH value,specific surface area,the total amount of heavy metals in sludge carbon and the percentage of residual state( F4) were all the maximum. At the same time,the bioavailable concentration( F1+F2) of heavy metals dropped to the minimum. In other words,the ecological risk of the heavy metals contained in the sludge was minimized. However,when the temperature was raised to 850 ℃,the percentage of stable heavy metal speciation( F3+F4) declined to some extent,which might be caused by volatilization of metals with pyrolysis gas at high temperature. The outcomes of this study implies that 700 ℃ was the optimal temperature for improving sludge biochar,immobilizing the heavy metals in sludge and minimizing their ecological risk.
引文
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[22]范世锁,汤婕,程燕,等.污泥基生物炭中重金属的形态分布及潜在生态风险研究[J].生态环境学报,2015,24(10):1739-1744.
[23]郭子逸,邵敬爱,王贤华,等.污泥微波热解过程重金属转化特性与风险评估[J].环境工程学报,2017,11(3):1801-1806.
[24] Chen F F,Hu Y Y,Dou X M,et al. Chemical forms of heavy metals in pyrolytic char of heavy metal-implanted sewage sludge and their impacts on leaching behaviors[J]. Journal of Analytical and Applied Pyrolysis,2015,116:152-160.
[25]关若楠,时亚飞,梁莎,等.复合调理脱水污泥热解残渣中重金属形态分布[J].环境科学与技术,2017,40(3):74-78.
[2] Kinga B,Anna M,Zofia P. The urgent need for risk assessment on the antibiotic resistance spread via sewage sludge land application[J]. Environment International,2016,87:49-55.
[3]程伟凤,李慧,杨艳琴,等.城市污泥厌氧发酵残渣热解制备生物炭及其氮磷吸附研究[J].化工学报,2016,67(4):1541-1548.
[4] Jin J,Li Y,Zhang J,et al. Influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochars derived from municipal sewage sludge[J]. Journal of Hazardous Materials,2016,320:417-426.
[5] Jin J,Wang M,Cao Y,et al. Cumulative effects of bamboo sawdust addition on pyrolysis of sewage sludge:biochar properties and environmental risk from metals[J]. Bioresource Technology,2017,228:218-226.
[6] Anna Z,Patryk O. Effect of pyrolysis temperatures on freely dissolved polycyclic aromatic hydrocarbon(PAH)concentrations in sewage sludge-derived biochars[J]. Chemosphere,2016,153:68-74.
[7] Yuan H R,Lu T,Huang H Y,et al. Influence of pyrolysis temperature on physical and chemical properties of biochar made from sewage sludge[J]. Journal of Analytical and Applied Pyrolysis,2015,112:284-289.
[8] Evita A,George B,Dimitrios K,et al. Biochar production by sewage sludge pyrolysis[J]. Journal of Analytical and Applied Pyrolysis,2013,101:72-78.
[9]张辰,王逸贤,谭学军,等.城镇污水处理厂污泥处理稳定标准研究[J].给水排水,2017,53(9):137-140.
[10] Chen T,Huang Q,Gao D,et al. Heavy metal concentrations and their decreasing trends in sewage sludges of China[J]. Acta Scientiae Circumstantiae,2003,23:561-569.
[11]沈伯雄,张增辉,李力,等.热解终温对污泥热解残渣特性的影响[J].环境污染与防治,2011,33(2):7-11.
[12]吕丰锦,刘俊新.我国南北方城市污水处理厂污泥性质比较分析[J].给水排水,2016,52(增刊1):63-66.
[13]王兴栋,张斌,余广炜,等.不同粒径污泥热解制备生物炭及其特性分析[J].化工学报,2016,67(11):4808-4816.
[14] Hossain M K,Strezov V,Chan K Y,et al. Influence of pyrolysis temperature on production and nutrient properties of wastewater sludge biochar[J]. Journal of Environmental Management,2011,92:223-228.
[15]肖瑞瑞,陈雪莉,周志杰,等.温度对生物质热解产物有机结构的影响[J].太阳能学报,2010,31(4):491-496.
[16] Zhao Y,Feng D,Zhang Y,et al. Effect of pyrolysis temperature on char structure and chemical speciation of alkali and alkaline earth metallic species in biochar[J]. Fuel Processing Technology,2016,141:54-60.
[17] Webster R. Soil sampling and methods of analysis-edited by M.R.carter&E. G. gregorich[J]. European Journal of Soil Science,2008,59(5):1010-1011.
[18]郑凯琪,王俊超,刘姝彤,等.不同热解温度污泥生物炭对Pb2+、Cd2+的吸附特性[J].环境工程学报,2016,10(12):7277-7282.
[19] Tytlak A,Oleszczuk P,Dobrowolski R. Sorption and desorption of Cr(Ⅵ)ions from water by biochars in different environmental conditions[J]. Environmental Science and Pollution Research,2015,22(8):5985-5994.
[20]金俊伟.热解及添加生物质辅料对污泥中重金属的固定效应及生态风险评价[D].杭州:浙江农林大学,2017.
[21]于晓庆,董滨,何群彪,等.污水污泥和消化污泥热解过程中重金属迁移转化行为对比分析[J].净水技术,2017,36(12):27-32.
[22]范世锁,汤婕,程燕,等.污泥基生物炭中重金属的形态分布及潜在生态风险研究[J].生态环境学报,2015,24(10):1739-1744.
[23]郭子逸,邵敬爱,王贤华,等.污泥微波热解过程重金属转化特性与风险评估[J].环境工程学报,2017,11(3):1801-1806.
[24] Chen F F,Hu Y Y,Dou X M,et al. Chemical forms of heavy metals in pyrolytic char of heavy metal-implanted sewage sludge and their impacts on leaching behaviors[J]. Journal of Analytical and Applied Pyrolysis,2015,116:152-160.
[25]关若楠,时亚飞,梁莎,等.复合调理脱水污泥热解残渣中重金属形态分布[J].环境科学与技术,2017,40(3):74-78.